You want to run the RuneUI on the Raspi but use a remote MPD on the uRendu ? There are so many info on the RuneUI that I don't know if __all__ of them can be gathered from a remote MPD running.
-- Aquarius Hifi Gear: RuneAudio/Volumio on Raspberry Pi B + Hifibery Digi, Atoll ST200 (network streamer, DAC, pre-amp), Emotiva XPA-2, Bowers & Wilkins 683